The present invention relates to a semiconductor device of a light emitting diode (LED) array and the likes, in which a plurality of light emitting elements is arranged; a light emitting diode (LED) head including the semiconductor device; and an image forming apparatus including the light emitting diode (LED) head.
In a conventional image forming apparatus such as a printer using electro-photography technology, a plurality of light emitting diodes (LEDs) is arranged to form an LED array chip, and a plurality of the LED array chips is arranged to form a light emitting diode (LED) head. Recently, it has been required that an image forming apparatus such as a printer forms an image with high resolution. Accordingly, the number of the light emitting elements in the LED print head has increased drastically.
In the LED array chip, an impurity is diffused in a surface of a semiconductor compound wafer (such as GaAs) through solid phase diffusion to form a plurality of p-n connection areas. A wiring pattern is connected to an upper layer of the p-n connection areas for switching ON/OFF. A common layer is disposed at a lower side (intermediate side of the substrate) of the p-n connection areas (refer to Patent Reference).    Patent Reference Japanese Patent Publication No. 10-035011
In the conventional LED array chip, the p-n connection areas have a very small size. Accordingly, it is necessary to reduce a size of the wiring pattern as well for securing insulation between the adjacent p-n connection areas. Further, the wiring pattern is connected to an electrode pad to be connected to a drive element over a relatively long distance, thereby increasing a potential difference between connecting portions and lowering energy efficiency.
In view of the problems described above, an object of the present invention is to provide a semiconductor device with improved energy efficiency and lowered resistance in a wiring pattern. A further object of the present invention is to provide an LED head using the semiconductor device, and an image forming apparatus having the LED head as an exposure device.
Further objects and advantages of the invention will be apparent from the following description of the invention.